Abstract The mechanism of polymerization of acrylonitrile initiated by the mannitol-Ce(IV) redox system has been studied in aqueous sulfuric acid medium in the temperature range 30 to 40° C. Experimental findings show that when the ceric ion concentration is held low (0.00005–0.02 M), the mechanism of polymerization is consistent with the kinetic scheme involving initiation by primary radicals and termination by growing polymer radicals. But when the ceric ion concentration exceeds 0.02 M, the linear mode of termination seems to operate. The effect of certain salts, acids, solvents, and temperature on the rate of polymerization (Rp) and the rate of metal ion disappearance (RCe) has also been investigated, and various rate and energy parameters have been evaluated.